His set up might not need to watch humidity if he has a humidifier going in the room or lives in a naturally humid place. I personally would be worried about too dry of air cracking the snakes' lung linings and opening up the opportunity for bacterial RI if left in too dry of an environment for too long.
Thats why it's best to give the ranges needed for temps and humidity and then each person's setup is catered to achieve said temps and humidity. Thats why i find it funny when people say stuff like "RHPs are the best" or "belly heat is the best". There is no 'best'. There is what works to achieve the goal needed for the snake.